1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to converting an interlaced format into a progressive format, and more particularly, to motion adaptive deinterlacing, which performs deinterlacing directly on a current video field to which temporal interpolation is applied, without using signal information of a next video field after the current video field.
2. Description of the Related Art
In general, a video signal for an image is implemented in either an interlaced format or a progressive format. A video signal in the interlaced format includes a plurality of fields. In contrast, a video signal in the progressive format includes a plurality of frames. A complete frame of the video using an interlacing format is generated by interlacing lines of an odd field between lines of an even field.
A television (TV) video signal uses interlaced scanning for compressing a transmission frequency band. Since personal computers (PCs) or high-definition (HD) TVs use progressive scanning, to display a TV video signal, the PCs or HDTVs must generate additional video lines that are not included in an interlaced scanned video signal. In other words, a reproduction apparatus capable of processing a progressive video signal has to first convert the interlaced video signal into a progressive video signal. This conversion is referred to as deinterlacing or interlaced-to-progressive conversion (IPC).
FIG. 1 is a view for explaining a concept of general deinterlacing of video data.
Referring to FIG. 1, deinterlacing changes a field 110 including either horizontal even-numbered sample lines or horizontal odd-numbered sample lines into a frame 120. An output frame (F0({right arrow over (x)},n)) is defined as follows:
                                          F            0                    ⁡                      (                                          x                →                            ,              n                        )                          =                  {                                                                                          F                    ⁡                                          (                                                                        x                          →                                                ,                        n                                            )                                                        ,                                                                                                  (                                                                  y                        ⁢                                                                                                  ⁢                        mod                        ⁢                                                                                                  ⁢                        2                                            =                                              n                        ⁢                                                                                                  ⁢                        mod                        ⁢                                                                                                  ⁢                        2                                                              )                                    ,                                                                                                                                                F                      i                                        ⁡                                          (                                                                        x                          →                                                ,                        n                                            )                                                        ,                                                                              otherwise                  ,                                                                                        (        1        )            
where {right arrow over (x)} denotes a spatial position, n denotes a field number, F({right arrow over (x)},n) denotes an input field, and Fi({right arrow over (x)},n) denotes a pixel to be interpolated.
As can be seen from FIG. 1, a resolution of the interlaced video signal is halved in comparison to the progressive scan video signal. In a case of a 480/60i resolution of the National Television Standard Committee (NTSC) standard, a single frame is divided into two 240-line fields and the 240-line fields are displayed one after the other every 1/60 seconds. This interlacing allows video data to be transmitted to a low-performance cathode ray tube (CRT) using a small amount of data, but a disadvantage occurs in that a fast scene or a complex image cannot be presented in detail.
FIG. 2 is a view for explaining temporal interpolation with respect to a current video field according to a related art deinterlacing method.
Referring to FIG. 2, when a current input field is an nth video field 220, for interpolation with respect to a line of the nth video field 220, pixel data information of a line of a previous field, i.e. an (n−1)th video field 210, which corresponds to the line of the nth video field 220, and pixel data information of a line of the next field, i.e. an (n+1)th video field 230, which corresponds to the line of the nth video field 220, are referred to. In other words, when the nth video field 220 is an even field and a bottom field, the nth video field 220 has video information of only even lines. Information for an empty line portion 221 is interlaced by referring to a portion 211 corresponding to the empty line 221 in the (n−1)th video field 210 that is an odd field and a top field, and temporally precedes the nth video field 220, and a portion 231 corresponding to the empty line 221 in the (n+1)th video field 230 that is an odd field and a top field, and temporally follows the nth video field 220.
FIG. 3 is a functional block diagram of an apparatus for motion adaptive deinterlacing in a related art deinterlacing apparatus.
Referring to FIG. 3, the related art deinterlacing apparatus includes a first field memory 320 and a second field memory 310 for storing, managing, and delaying an interlaced video signal input from an input unit 305, a motion detection unit 330 for determining whether or not a pixel as well as an object between fields has motion, a spatial interpolation unit 340 for performing spatial interpolation as an interpolation unit for interpolation with respect to each field, a temporal interpolation unit 350 for temporal interpolation, and an adaptive mixer 360 for performing spatial interpolation, temporal interpolation, or a combination thereof according to the determined motion.
An interlaced video signal is input to the input unit 305, and the first field memory 320 stores a previous (n−1)th video field. The second field memory 310 stores the current nth video field and performs interpolation with respect to that video field. Since it should be first determined that a line portion to be interpolated has no motion to perform temporal interpolation, input of a next (n+1)th video field, i.e., a video field after the current nth video field, is waited for. Once the (n+1)th video field is received, the (n+1)th video field is compared with the (n−1)th video field stored in the first field memory 320. If it is determined that the line portion to be interpolated has no motion since the difference between data values of the previous (n−1)th video field and the next (n+1)th video field is small, the temporal interpolation unit 350 receives the previous (n−1)th video field and the next (n+1)th video field and performs interpolation with respect to the previous (n−1)th video field and the next (n+1)th video field by referring to data of the line portion to be interpolated in the current nth video field (as illustrated by the dotted line which inputs into the temporal interpolation unit 350).
On the other hand, if it is determined that the line portion to be interpolated has motion since the difference between the previous (n−1)th video field and the next (n+1)th video field is large, lines above and below the current nth video field may have low correlation with each other. In this case, the spatial interpolation unit 340 performs intra field interpolation such as slope correlation interpolation using the current nth video field.
However, during the related art interlacing process described above, the signal of the next field following the current field is required for interpolation. Subsequently, a temporal field delay occurs between the input and the output, resulting in a video delay which is noticeable by a user.